Abstract:

The invention relates to an electroluminescent organic-inorganic hybrid
material which is characterised in that it comprises: at least one
microporous or mesoporous solid having a structure that is selected from
among the structures of zeolites, porous oxides, molecular sieves,
silicoaluminophosphates and aluminosilicates; and at least one organic
compound which confers electroluminescent properties thereto. The
invention is also characterised in that the organic compound is a
polycyclic aromatic hydrocarbon, at least part of which is joined to the
structure of the microporous or mesoporous solid using covalent bonds.
The invention also relates to the method of obtaining said material and
to the use thereof.

Claims:

1. An electroluminescent organic-inorganic hybrid material which
comprises:at least one microporous or mesoporous solid having a structure
that is selected from among the structures of zeolites, porous oxides,
molecular sieves, silicoaluminophosphates and aluminosilicates, andat
least one organic compound which confers electroluminescent properties
thereto, and in which said organic compound is a polycyclic aromatic
hydrocarbon, at least part of which is joined to the structure of the
microporous or mesoporous solid by means of covalent bonds.

2. An electroluminescent hybrid material according to claim 1, which
comprises a mesoporous solid with a structure that corresponds to that of
an MCM-41 type silica.

3. An electroluminescent hybrid material according to claim 1, which
comprises a mesoporous solid with a structure that corresponds to that of
an MCM-48 type silica.

4. An electroluminescent hybrid material according to claim 1, which
comprises a mesoporous solid with a structure that corresponds to that of
an FSM-16 type silica.

5. An electroluminescent hybrid material according to claim 1, which
comprises a mesoporous solid with a structure that corresponds to that of
an SBA-15 type silica.

6. An electroluminescent hybrid material according to claim 1, wherein the
aromatic hydrocarbon is a derivative of 9,10-diphenylanthracene.

7. An electroluminescent hybrid material according to claim 1, wherein the
aromatic hydrocarbon is at least one derivative of the group consisting
of derivatives of pyrene, phenanthrene, rubrene, perylene and
tetraphenylporphyrin.

8. An electroluminescent hybrid material according to claim 7, wherein
said derivative comprises a core selected from among pyrene,
phenanthrene, rubrene, perylene and tetraphenylporphyrin bonded to
substituents which have terminal groups capable of bonding to silanol
groups by means of covalent bonds.

11. An electroluminescent hybrid material according to claim 1, wherein
said material furthermore contains housed in its structure a charge
transfer complex between a second aromatic hydrocarbon and an electron
donor compound.

12. An electroluminescent hybrid material according to claim 11, wherein
said second aromatic hydrocarbon is the same as the aromatic hydrocarbon
having covalent bonds with the microporous or mesoporous solid.

13. An electroluminescent hybrid material according to claim 11, wherein
said second aromatic hydrocarbon is different from the aromatic
hydrocarbon having covalent bonds with the microporous or mesoporous
solid.

14. An electroluminescent hybrid material according to claim 11, wherein
said electron donor compound is selected from among amines, aromatic
amines, phenols and ethers.

15. Method for preparing an electroluminescent organic-inorganic hybrid
material comprising:at least one microporous or mesoporous solid having a
structure that is selected from among the structures of zeolites, porous
oxides, molecular sieves, silicoaluminophosphates and aluminosilicates,
andat least one organic compound which confers electroluminescent
properties thereto, and in which said organic compound is a polycyclic
aromatic hydrocarbon, at least part of which is joined to the structure
of the microporous or mesoporous solid by means of covalent bonds,
characterised in that it comprises:a first stage of preparation of a
precursor which comprises a polycyclic aromatic hydrocarbon included in
its structure, anda second stage of conversion of said precursor into the
electroluminescent hybrid material.

16. Method according to claim 15, wherein said precursor is an
organosiliceous compound which includes the aromatic hydrocarbon.

17. Method according to claim 15, wherein the second stage consists of
reacting said precursor with a source of Si in the presence of a
structure directing agent.

19. Method according to claim 15, wherein the first stage of preparation
of the organosiliceous precursor comprises a coupling reaction catalysed
by palladium followed by the addition of a source of Si in the presence
of a structure directing agent.

20. Method according to claim 19, wherein said source of Si is
mercaptoalkyltrialcoxysilane.

21. Method according to claim 19, wherein said structure directing agent
is eliminated by means of a solid-liquid extraction.

22. An electroluminescent hybrid material according to claim 1, obtained
by means of a method which comprises preparing a microporous or
mesoporous solid starting from a precursor which consists of a polycyclic
aromatic hydrocarbon included in its structure.

23. An electroluminescent hybrid material according to claim 1, obtained
by means of a first stage of preparation of an organosiliceous precursor
which comprises a coupling reaction catalysed by palladium followed by
the addition of mercaptoalkyltrialkoxysilane in the presence of a
structure directing agent, which is then eliminated by means of a
solid-liquid extraction.

24. Method for the manufacture of light emitting systems which comprises
employing the electroluminescent hybrid material of claim 1 therein.

25. Method for the manufacture of a gas sensor which comprises employing
the electroluminescent hybrid material of claim 1 therein.

Description:

TECHNICAL FIELD OF THE INVENTION

[0001]The present invention comes within the technical field of micro- and
mesoporous solids such as zeolites, porous oxides, molecular sieves,
silicoaluminophosphates and aluminosilicates, combined with organic
compounds or metallic complexes, such as condensated polycyclic aromatic
compounds, and particularly those aromatic compounds which confer
electroluminescent properties.

STATE OF THE PRIOR ART OF THE INVENTION

[0002]Electroluminescence is a property consisting of the emission of
light when a compound, or more commonly a series of duly arranged
compounds, located between two electrodes, is subjected to a potential
difference. Electroluminescence is a physical phenomenon that arises when
a recombination of an electron and a positive charge takes place in a
molecule. The positive charge is known as an electron hole. The
recombination of an electron and a hole produces an excited electron
state of the molecule, which relaxes to the ground electron state by
means of emitting a photon (equation 1). The relaxation of an electron
state by means of the emission of light is a phenomenon known as
electroluminescence because the origin of the light emission is a
potential difference between two electrodes.

[0006]The positive electrode absorbs electrons from the material in
contact and produces positive holes which migrate towards the negative
electrode. The negative electrode injects electrons in the material that
is in contact with it and produces electrons. These migrate toward the
positive electrode. In order to favour the creation of holes and
electrons and their migration, it is common in the state of the art
relating to electroluminescent cells to place some films in contact with
the electrodes, having a thickness of the order of microns and made of
suitable materials for accepting holes or electrons. Between these films
a layer of an intermediate electroluminescent material is placed between
the injector layer of holes and the injector for electrons, which is
where the collapse of holes and electrons takes place and where the
recombination is produced. One of the electrodes (generally the anode) is
a transparent electrode which permits the light generated in the
electroluminescence phenomenon to be visible from outside the cell.

[0007]Included among electroluminescent materials are organic compounds.
As electroluminescent materials, organic compounds present the advantage
over inorganics of having a greater ease of synthesis and purification
along with the possibility of easily modifying the emission wavelength by
means of the introduction of appropriate substituents. Of special
importance in the present invention is the fact that polycyclic aromatic
compounds exhibit the phenomenon of electroluminescence. Charge transfer
complexes between a donor compound and a charge acceptor, where a
polycyclic aromatic compound intervenes, are also electroluminescent
materials. For a full list of this type of compound, consult Table 2,
page 3021, of the reference M. M. Richter, Electroluminescence, Chem.
Rev. 2004, 104, 3003-3036.

[0008]One of the main drawbacks of organic compounds as electroluminescent
materials is their durability, since they undergo decomposition due to
attack by atmospheric components. This decomposition is particularly
important during the operation of the electroluminescent cell. Oxygen is
a notably negative agent in the electroluminescence of organic compounds.
On the one hand, it can trap the radical ions involved in the
electroluminescence, triggering their degradation, and on the other hand
it can inhibit the emissive relaxation of the excited electron state by
means of inhibition phenomena. In particular, the deactivation of triplet
excited states by oxygen by means of an energy transfer process is very
well known in the field of organic photochemistry since it serves to
generate singlet oxygen.

[0009]Spanish patent application P200201588 describes an
electroluminescent material in which an electroluminescent compound
selected from among polyphenylenevinylene derivatives, metal ion
complexes of the 3A group with .box-solid.-hydroxyquinoline, and
combinations thereof, are housed in interior spaces of a matrix composed
of micro- and/or mesoporous materials, such as zeolites, porous oxides,
molecular sieves, silicoaluminophosphates and aluminosilicates. In this
prior art there does not exist any covalent bond between the organic
compound and the inorganic structure which acts as a matrix.

[0010]Moreover, the preparation of structured mesoporous organic-inorganic
hybrid materials is also known. These materials can be prepared starting
from organosiliceous compounds in the absence of or in combination with
tetramethyl orthosilicate or tetraethyl orthosilicate. The hydrolysis of
these compounds with trialcoxysilane groups under acidic or basic pH
conditions produces the polymerisation of the monomer with the formation
of the silicate containing organic compounds. The synthesis of these
materials requires a surfactant compound or structure directing agent
which, in aqueous medium, creates the first spatial inhomogeneity in a
way that is regular but non-rigid. Around the surfactant in aqueous
medium, the condensation/polymerisation of the organosiliceous compound
takes place, or the co-condensation of this organosiliceous compound and
of the orthosilicate. The surfactant agents most commonly used are
cetyltrimethylammonium bromide and the copolymer of ethyleneglycol and
propyleneglycol forming blocks. Pluronic is the trade name of some of
these types of neutral surfactants based on
polyethyleneglycol-polypropyleneglycol. The structure of the
organosiliceous material resulting therefrom can be identical to those
found described in the literature as MCM and SBA-15. By means of this
methodology, materials are obtained which, having an amorphous or
crystalline structure of silicon dioxide and organosilanes, present an
extraordinary periodicity in the distribution of channels and pores in
such a way that, owing to this regularity, a characteristic X-ray
diffraction pattern is produced. The channels have a regular size of the
order of nanometres (mesopores) and a very high surface area of greater
than 500 m2×g-1.

[0011]The present invention seeks to avoid, or at least reduce, the
problem of oxygen inhibition and degradation of electroluminescent
organic compounds in the presence of atmospheric agents.

DESCRIPTION OF THE INVENTION

[0012]The present invention relates to an electroluminescent
organic-inorganic hybrid material which is characterised in that it
comprises: [0013]at least one microporous or mesoporous solid having a
structure that is selected from among the structures of zeolites, porous
oxides, molecular sieves, silicoaluminophosphates and aluminosilicates,
and [0014]at least one organic compound which confers electroluminescent
properties thereto, and in which said organic compound is a polycyclic
aromatic hydrocarbon, at least part of which is joined to the structure
of the microporous or mesoporous solid by means of covalent bonds.

[0015]In this material, a protection of the polycyclic aromatic
hydrocarbon is produced which confers electroluminescent properties in
view of the fact that this hydrocarbon is included inside the structured
microporous or mesoporous organosiliceous hybrid material, which means
that attack from chemical agents present in the environment is prevented
owing to a restricted diffusion and to a confinement effect.

[0016]In accordance with a preferred embodiment of the invention, at least
part of the polycyclic aromatic hydrocarbon is included in the same
structure of the microporous or mesoporous solid by means of covalent
bonds.

[0017]In accordance with preferred embodiments of the invention, the
structure of the mesoporous solid can be a silica of the type MCM, such
as for example that of an MCM-41 type silica or that of an MCM-48 type
silica or that of other silicas, such as for example FSM-16 type silica
or SBA-15 type silica.

[0018]The polycyclic aromatic hydrocarbon can in turn be at least one
derivative of 9,10-diphenylanthracene, a derivative of the group
consisting of derivatives of pyrene, phenanthrene, rubrene, perylene and
tetraphenylporphyrin.

[0019]In this specification, derivative of the polycyclic aromatic
hydrocarbon is understood to be an aromatic hydrocarbon having
substituents which possess terminal groups capable of bonding to silanol
group by means of covalent bonds. Said terminal groups preferably
comprise atoms selected from among oxygen, sulphur, nitrogen, silicon and
combinations thereof, and more preferably yet they comprise atoms of
silicon.

[0020]The electroluminescent hybrid material of the invention can
furthermore contain housed in its structure one or more charge transfer
complexes between a second aromatic hydrocarbon and an electron donor
compound. Said second aromatic hydrocarbon can be the same as the
aromatic hydrocarbon having covalent bonds with the microporous or
mesoporous solid, or it can be different from the aromatic hydrocarbon
having covalent bonds with the microporous or mesoporous solid.

[0021]Said electron donor compound can be selected, for example, from
among amines, aromatic amines, phenols and ethers.

[0022]The present invention also refers to a method for preparing an
electroluminescent organic-inorganic hybrid material comprising:
[0023]at least one microporous or mesoporous solid having a structure
that is selected from among the structures of zeolites, porous oxides,
molecular sieves, silicoaluminophosphates and aluminosilicates, and
[0024]at least one organic compound which confers electroluminescent
properties thereto, and in which said organic compound is a polycyclic
aromatic hydrocarbon, at least part of which is joined to the structure
of the microporous or mesoporous solid by means of covalent bonds,
characterised in that it comprises: [0025]a first stage of preparation of
a precursor which comprises a polycyclic aromatic hydrocarbon included in
its structure, and [0026]a second stage of conversion of said precursor
into the electroluminescent hybrid material.

[0027]According to preferred embodiments of the method, said precursor is
an organosiliceous compound which comprises the aromatic hydrocarbon.

[0028]According to particular embodiments of the method, the second stage
consists of causing said precursor to react with a source of Si in the
presence of a structure directing agent. Said structure directing agent
can optionally be eliminated by solid liquid extraction.

[0029]The hybrid materials of the present invention can also be obtained
starting from an organosiliceous precursor in which there is already
present the aromatic hydrocarbon or a derivative thereof prepared--as
defined earlier--by a coupling reaction catalysed by palladium followed
by the addition of a source of Si, such as for example
mercaptoalkyltrialcoxysilane in the presence of a structure directing
agent which can then be eliminated by means of a solid-liquid extraction
which is in itself conventional in the preparation of organosiliceous
materials.

[0030]In a preferred embodiment of this invention, the structured
mesoporous organic/inorganic hybrid materials are organosiliceous
materials with a base structure of the type MCM-41 or SBA-15, but which
contain a polycyclic aromatic hydrocarbon in their structure which give
them an electroluminescent response.

[0031]The preparation of these solid materials can be carried out in two
differentiated phases. The first is the synthesis of the organosiliceous
precursor as indicated above, and the second is the preparation of the
structured microporous or mesoporous solid.

[0032]The synthesis of the organosiliceous compound used as precursor of
the solid material is carried out by any of the usual techniques in
organic synthesis. According to particular embodiments, in order to
obtain the precursor of the electroluminescent material of the present
invention, a methodology is followed having general application for the
preparation of any kind of aromatic organosiliceous precursor consisting
of the concatenation of two reactions shown in diagrammatic form in the
following equation:

[0033]It can be seen that the first of the reactions leads to the
formation of C--C bonds by means of coupling by the Suzuki-Miyaura
reaction catalysed by palladium compounds and which leads to the
synthesis of a suitable aromatic hydrocarbon containing vinyl groups in
the periphery, while the second reaction serves to introduce
trialcoxysilane groups in terminal positions and consists of the addition
of mercapto groups to vinyl groups by means of a chain mechanism
initiated by radicals.

[0034]Following the stage of synthesis of the organosiliceous precursor,
the next step is to prepare the structured mesoporous material either by
hydrolysis under acid pH conditions using Pluronic (Pluronic is a
tri-block polymer which has a hydrophobic central part of propyleneglycol
groups and two external parts of hydrophilic ethyleneglycol groups, a
polymer with 40 ethyleneglycol groups attached to 70 propyleneglycol
groups and terminated with another 40 ethyleneglycol
groups--ethyleneglycol 40 propyleneglycol 70 ethyleneglycol 40--being
preferable) as structure directing agent or under basic pH conditions
using cetyltrimethylammonium bromide as surfactant. In both cases,
variable quantities of tetraethyl orthosilicate can be added to the
organic compound as another source of silicon atoms in addition to the
organic compound. The synthesis medium is water but variable quantities
of other organic solvents miscible with water can be added with the aim
of promoting the dissolution of the organic component in the water until
a transparent gel is obtained. The addition of the components must be
done at a temperature of between 0 and 20° C. with stirring and
these conditions must be maintained for a period of time. Following the
mixing of the components (surfactants, pH agent, organosiliceous
precursor with or without tetraethyl orthosilicate), the gel is
transferred to a polypropylene bottle which can be hermetically sealed
and is heated to a temperature of between 80 and 120° C. for a
period of several days.

[0035]The resulting solid is collected and washed exhaustively. The
material thus obtained is electroluminescent, as is that resulting from
extracting the structure directing agent. This extraction can be carried
out using water acidulated to pH 3 with hot hydrochloric acid or an
organic solvent such as 3:1 mixture of heptane/ethanol containing
hydrochloric acid. The complete extraction of the structure directing
agent is most commonly done by carrying out a consecutive series of
extractions combining different solvents.

[0037]i) characteristic X-ray diffraction pattern with a peak at angles
less than 2.5° as a function of the distance between the centres
of the channels.

[0038]ii) Isothermal adsorption of gas with a type IV profile according to
the nomenclature of the IUPAC and which corresponds to mesoporous
materials. The pore size varies between 2.5 and 6 nm and the BET surface
area is greater than 500 m2×g-1.

[0039]iii) Transmission electron microscopy images in which the apertures
of the channels can be seen when the image is frontal or the parallel
arrangement of the channels can be seen when the image is lateral.

[0040]In addition, these materials have the analytical and spectroscopic
characteristics of organic/inorganic hybrid materials. In particular:

[0041]i) In solid state NMR-29Si spectroscopy, together with the
characteristic peaks of tetra- (Q4) and tripodal (Q3) silicons
at -110 and -95 ppms, the presence can also be seen of other Si signals
between -60 and -90 ppms and which correspond to those of the organic
precursor which are found tri- (T3) and tetrapodally (T4)
connected to the structure of the solid. The existence of these silicons
is proof that the organosilane component is covalently bonded to the
structure of the solid since the chemical displacement of the
organosilane precursor in solution prior to condensing in the solid is
higher than -50 ppms.

[0042]ii) In IR spectroscopy, together with the characteristic bands of
the silicate, of the silanol groups and of the co-adsorbed water,
vibration peaks in the aromatic region (1620-1400 cm-1) are also
observed indicating the presence of the aromatic component. These
aromatic bands persist following the extraction of the structure
directing agent and they remain unaltered when the material is heated to
a temperature of 300° C. or below at a reduced pressure of
10-2 Pa for 1 h.

[0043]iii) In UV-Vis spectroscopy recorded by the method of diffuse
reflectance of the solid, absorption bands characteristic of aromatic
compounds appear in the near UV or visible and can have a fine
vibrational structure.

[0044]iv) In emission spectroscopy, these solids emit visible light when
they are excited at the wavelength of the absorption maximum. Though
shorter and with several components, the emission lifetimes are in the
nanosecond range and are those corresponding to the singlet state.

[0045]Moreover, the most relevant characteristic with regard to the
present invention is that these solids, as with the polycyclic aromatic
compounds from which they derive, behave as electroluminescent materials.
Alternatively, the phenomenon of electroluminescence can require the
adsorption in this material of another component in order to form a
charge transfer complex with the polycyclic aromatic component forming
part of the material or with another aromatic hydrocarbon different from
that forming part of the material.

[0046]In order to observe this property, a fine film of this material is
arranged on a transparent conductor electrode of indium-tin oxide (ITO)
and a cell is constructed with an aluminium cathode. This cell can be
completed by adding other layers which inject holes or electrons in order
to increase the efficacy of the electroluminescence. Equally, an
electrolytic solution can be added, with polyacrylates and
polyethyleneglycols being especially effective here since they improve
the conductivity. In the same way, electroluminescence is observed with
these materials when electroluminescent cells are prepared using any
other technique constituting the state of the art in the preparation of
these cells. The emission of light is observed when a direct current
potential of between 2.5 and 7 V is applied to the electrodes. A
fluctuating potential can also be applied.

[0047]The electroluminescent hybrid materials of the present invention has
use for example in light emitting systems such as LEDs. On account of
their porous composition they are also useful as gas sensors in order to
determine, for example, the composition and presence of ammonia, water,
carbon monoxide and other component in effluent gases.

BRIEF DESCRIPTION OF THE FIGURES

[0048]Appearing as an integral part of this descriptive specification is a
series of diagrams in which FIGS. 1A and 1B are transmission microscope
images in which the material 4/MCM-41 is respectively observed with a
front view and a side view of the pores;

[0049]FIG. 2 shows an NMR-29Si spectrum of solids recorded for the
sample 4/MCM-41-ex in Broker equipment at 300 MHz, in which the sample is
rotating at 5 kHz in magic angle;

[0050]FIG. 3 shows an electroluminescence spectrum recorded with a direct
current potential of 4.5 V of samples containing a polycyclic aromatic
hydrocarbon covalently bonded to structures MCM-41 and SBA-15;

[0051]FIG. 4 shows an LED structure in which an organosiliceous hybrid
material has been used.

MODES OF EMBODYING THE INVENTION

[0052]According to a particular embodiment, an electroluminescent material
is prepared containing 9,10-diarylanthracene forming part of a structured
mesoporous organic/inorganic hybrid solid. The required precursor is
obtained starting from 9,10-dibromoanthracene (6 g, 18 mmol) which is
coupled to p-vinylphenylboronic acid (7.98 g, 54 mmol) in excess using as
palladium catalyst a mixture of the complex of palladium with
dibenzylideneacetone and palladium bis(tributylphosphine) (100:30 mg,
respectively) in the presence of potassium carbonate (8.2 g) and in dry
toluene (300 ml) as solvent. The reaction is carried out at reflux
temperature, under an inert atmosphere and for a period of time of 48
hours. The reaction mixture is purified by column chromatography, with
80% of the corresponding 9,10-bis(4-vinylphenyl)anthracene being
obtained.

[0053]This intermediate (2.5 mmol) is immediately made to react in toluene
(10 ml) with 3-mercaptopropyltriethoxysilane (5 mmol) in an argon stream
and using AIBN (1.25 mmol) as radicals initiator. The mixture is kept
under magnetic stirring at 90° C. for 6 h. After that time, the
solvent is evaporated at reduced pressure and the residue is exhaustively
washed with hexane in order to eliminate the excess of reagents. In this
way the compound
9,10bis(4-[2-(3-trimethoxysilylpropylthio)ethyl]anthracene (compound
number 4 in equation 3) is obtained.

[0054]Once the precursor 4 has been obtained, it is condensed with
tetraethyl silicate in the presence of cetyltrimethyl ammonium bromide
(CTAB) in order to give a structured mesoporous material. The molar ratio
of the preferred example contains: 1.00 Si:0.12 CTAB:8.0 NH3 (28%):
114H2O. The experimental procedure consists of adding the structure
directing agent CTAB (0.45 g) to an aqueous solution of NH4OH
(10.349 g, 28% by weight) in deionised water (13.75 g) and stirring the
solution for 30 min in a polyethylene bottle until a homogenous solution
is formed at a temperature of 10° C. To this cold solution are
added the compounds 4 (0.4 g) and tetraethyl orthosilicate (2.04 g)
dissolved in 2 ml of a 1:1 mixture of acetone/water. The mixture is left
to slowly reach room temperature while the stirring is continued for 2 h.
After that time, the resulting gel is heated at 100° C. without
stirring for 4 days. The solid resulting in these conditions is
exhaustively washed with distilled water (1.5 L). The structure directing
agent can be extracted by shaking the solid with an ethanol solution (10
ml per gram of solid) of 0.05 M hydrochloric acid at 50° C. for 3
h. The extraction is them immediately continued with a solution of
ethanol/heptane (50:50) containing 0.15 M hydrochloric acid at 90°
C. for 3 h using a solid:solvent ratio is 10:1. The resulting solids are
hereafter referred to as 4/MCM-41 and 4/MCM-41-ex depending on whether
they refer to the extracted or unextracted material.

[0055]The solids 4/MCM-41 and 4/MCM-41-ex present transmission microscopy
images where the presence of channels can be seen of dimensions 3 nm and
having a regular distribution as shown in FIG. 1.

[0056]i) In NMR-29Si the signals Q4 and Q3 are observed
corresponding to the tetra- and tripodal silicons connected to four atoms
of oxygen together with a signal of lesser intensity at -75 ppm
corresponding to the atoms of silicon tripodally connected to the
structure of the solid and to the CH2 group of the organic compounds
(T3). One of these NMR-29Si spectra is shown in FIG. 2.

[0057]In photoluminescence spectroscopy, the solids 4/MCM-41 and
4/MCM-41-ex exhibit an emission characteristic of the anthracene group
present in the structure when excited at the wavelength of the absorption
maximum. Moreover, these samples emit electroluminescence when a layer of
this material is taken starting from an aqueous suspension of the solid
between an ITO electrode and another made of aluminium and the electrodes
are subjected to a potential of 4.5 Vdc. This electroluminescent emission
is also observed in other materials forming the object of the present
invention, as shown in FIG. 3, in which can be seen electroluminescence
spectra recorded with a potential of 4.5 Vdc of the samples containing
the compound 4 covalently bonded to an MCM-41 structure prior to
extracting ( ) and after extracting (.star-solid.) the structure
directing agent, and also the spectra of compound 4 forming part of the
SBA-15 structure prior to extracting (.box-solid.) and after extracting
(.box-solid.) the structure directing agent.

[0058]In FIG. 4 an OLED structure can be observed consisting of a cathode
1 in the form of a metallic layer and a crystal substrate which
constitutes the anode 4. The cathode 1 and anode 4 are connected to a
direct current electrical circuit 7 of between 2 and 10 V. Between the
cathode 1 and the anode are an electrode transport layer 2 and an
electroluminescent layer 5 which emits light in the direction of the
arrows through the crystal substrate constituting the anode.

EXAMPLE 2

[0059]75 ml of an aqueous solution of 0.007 M nitric acid is prepared to
which is added at 60° C. and with moderate stirring 5 ml of an
aqueous solution containing 4.5 mmol of the compound
9,10-anthrylene-bis(4-phenylene-propyl-thioproppyltrimethoxysilane)
(compound 4). The mixture is kept being stirred at 60° C. for
between 1 and 3 minutes and 20 ml of a 1.45 M solution of ammonium
hydroxide is added in order to raise the pH of the mixture and favour the
condensation of the solid. The mixture is kept being stirred at the same
temperature for 1 h, and finally the solid formed is collected by
centrifugation (at 6000 rpm for 15 min) and it is repeatedly washed with
H2O and left to dry in a desiccator. Once dry, the resulting solid
possesses a surface area of around 350-400 m2 g-1, with pores
within the microporosity range.